title: Osteopontin stimulates autophagy via integrin/CD44 and p38 MAPK signaling pathways in vascular smooth muscle cells.
abstract: Osteopontin (OPN) exerts pro-inflammatory effect and is associated with the development of abdominal aortic aneurysm (AAA). However, the molecular mechanism underlying this association remains obscure. In the present study, we compared gene expression profiles of AAA tissues using microarray assay, and found that OPN was the highest expressed gene (>125-fold). Furthermore, the expression of LC3 protein and autophagy-related genes including Atg4b, Beclin1/Atg6, Bnip3, and Vps34 was markedly upregulated in AAA tissues. To investigate the ability of OPN to stimulate autophagy as a potential mechanism involved in the pathogenesis of this disease, we treated vascular smooth muscle cells (SMCs) with OPN, and found that OPN significantly increased the formation of autophagosomes, expression of autophagy-related genes and cell death, whereas blocking the signal by anti-OPN antibody markedly inhibited OPN-induced autophagy and SMC death. Furthermore, inhibition of integrin/CD44 and p38 MAPK signaling pathways markedly abrogated the biological effects of OPN on SMCs. These data for the first time demonstrate that OPN sitmulates autophagy directly through integrin/CD44 and p38 MAPK-mediated pathways in SMCs. Thus, inhibition of OPN-induced autophagy might be a potential therapeutic target in the treatment of AAA disease. J. Cell. Physiol. 227: 127-135, 2012. © 2011 Wiley Periodicals, Inc.
authors.affiliation: Department of Vascular Surgery, Peking Union Medical Hospital, Beijing, China.
authors.forename: Yue-Hong
authors.initials: YH
authors.lastname: Zheng
authors.forename: Cui
authors.initials: C
authors.lastname: Tian
authors.forename: Yan
authors.initials: Y
authors.lastname: Meng
authors.forename: Yan-Wen
authors.initials: YW
authors.lastname: Qin
authors.forename: Ya-Hao
authors.initials: YH
authors.lastname: Du
authors.forename: Jie
authors.initials: J
authors.lastname: Du
authors.forename: Hui-Hua
authors.initials: HH
authors.lastname: Li
mesh_terms: D017544:Aortic Aneurysm, Abdominal / Q000378:metabolism; D001343:Autophagy / Q000502:physiology*; D015153:Blotting, Western; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism*; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D016023:Integrins / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D053495:Osteopontin / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: C497483:CD44 protein, human; D018960:Hyaluronan Receptors; D016023:Integrins; D053495:Osteopontin; D048051:p38 Mitogen-Activated Protein Kinases